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From: woodside@ttidca.UUCP
Newsgroups: comp.sys.atari.st
Subject: Re: Blowing up hardware with software
Message-ID: <663@ttidca.TTI.COM>
Date: Wed, 29-Apr-87 11:01:22 EDT
Article-I.D.: ttidca.663
Posted: Wed Apr 29 11:01:22 1987
Date-Received: Sat, 9-May-87 06:49:53 EDT
References: <8704241627.AA03826@yale-eli.arpa> <561@maccs.UUCP> <1288@ubc-cs.UUCP> <1776@husc6.UUCP>
Reply-To: woodside@ttidcb.UUCP (George Woodside)
Distribution: world
Organization: Citicorp/TTI, Santa Monica
Lines: 20


The old Compucolor II computer from ISC was very vulnerable to certain
hardware tinkering. This was an 8080 machine, with 48K of RAM, and 16K of
ROM/hardware registers. Tampering with the addresses that accessed the
hardware registers could wipe out all the RAM (it did something fatal to the
refresh logic). It used an Intel CRT controller for screen processing.
Altering the number of scanlines to too high a value could kill the CRT.

The ROM contained a ripped-off version of Microsoft BASIC and a simplistic
file system. Microsoft found out about them, and forced ISC to become a
Microsoft distributor. They also collected royalties on all machines sold
up to that time.

The real comedy of this box was the disk drive. The thing was originally
designed to use an 8-track tape cartridge for storage (yes, you read that
right!). When that proved to unreliable, they switched to a 5.25 inch
disk dirve. They didn't change the file system, which still thought it
was a tape drive. When you deleted a file, it re-packed all remaining files
back to the front of the disk. Used the 8K of screen RAM for a buffer to
do it, which led to some psychedelic I/O.